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    <meta charset="UTF-8">
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    <title>Document</title>
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<body>
    <script>
        let calculate = (
            function yyg() {
                let a = 20;
                let b = 10;
                function add() {
                    return a + b;
                }
                function sub() {
                    return a - b;
                }
                return {
                    add,
                    sub
                }
            }
        )()
        let result1 = calculate.add()
        let result2 = calculate.sub()
        console.log(result1, result2)
    </script>

</body>

</html>